Win7 64-bit works great. Just don't try to run 64-bit versions of Internet Explorer or Firefox -- you will run into all sorts of things that don't work. The 32-bit versions of these browsers work fine in 64-bit Win7.

Axiom M80s + QS8s + VP180 <-- Pioneer VSX-1120-K <-- Squeezebox Touch / XBox360 / Oppo BDP-93